Carry-over effects of winter conditions on nesting <i>Somateria fischeri</i> (Spectacled Eider), a sea ice-associated sea duck

Abstract Climate change in the Arctic is occurring more rapidly than anywhere on the globe and changes in the marine environment can impact the distribution and abundance of Arctic and subarctic marine species. Understanding how a species responds to climate change can aid conservation planning and recovery. Somateria fischeri (Spectacled Eider) winter in the Bering Sea and breed along coastal areas of Alaska and Arctic Russia. The severity of winter conditions in the Bering Sea has been associated with both reduced annual survival and reduced breeding abundance and may have sublethal effects during the breeding season. In this study, we used long-term nest monitoring data from 2 sites in Alaska; Kigigak Island, a subarctic site on the coast of the Bering Sea, and Utqiaġvik, on the Arctic coast, to examine the hypothesis that winter conditions in the Bering Sea influence the reproductive performance of eiders in the following breeding season. For both sites, we examined the effects of winter ice conditions, spring temperature, and spring wind in the Bering Sea wintering area on nest initiation date, clutch size, and nest survival. Nest initiation date was not strongly associated with conditions in the wintering area experienced prior to the breeding season and mean initiation date was 20 days later at the Arctic site, Utqiaġvik, than at the subarctic site, Kigigak Island. We found no evidence that winter and spring conditions on the wintering area preceding the breeding season explained variation in clutch size. Nest survival varied by year and site and increased asymptotically with increasing sea ice cover at both sites. We speculate that low sea ice winters reduce nest survival through negative effects on body condition. Negative effects of changing ice conditions on multiple demographic rates may lead to future population declines for S. fischeri at rates higher than previously predicted.